A number of investigations are attempting to identify endogenous hormones related to risk of breast, endometrial, cervical, testicular and prostate cancers. In these studies, attention is focusing not only on classically accepted hormones, but also on some newly suggested predictors, including insulin-like and other growth factors. Relationships with breast diseases (including cancer) have been pursued using data from the Mayo Serum Bank as well as a case-control study among Asian-American women. Further follow-up of participants in the Columbia, Missouri component of the Mayo Serum Bank is being pursued to expand upon previous findings and to enable additional hypotheses to be addressed. Follow-up of a cohort of women screened for bone density is being planned to better understand how bone density relates to subsequent risk of breast, endometrial and other cancers. In previous research, we were able to demonstrate the importance of selected endogenous hormones in the etiology of endometrial cancer. Current research is attempting to expand upon these observations by assessing interrelationships with genetic markers and by studing relationships within defined subgroups of tumors. Although cervical cancer has not generally been recognized as a hormonally-related tumor, a number of risk factors, including parity and exogenous hormone use, support the need for further study of hormonal factors. Within the context of a large natural history study, we are attempting to assess the role of endogenous hormones to cervical abnormalities, particularly as they affect the progression and persistance of infection with the human papillomaviruses. Our interest in endogenous hormones also extends to testicular cancers, where we are collaborating with the Department of Defense in a study of military recruits for whom pre-diagnostic sera are available. Efforts continue to identify risk factors for prostate cancer. In a multi-disciplinary case-control study that we undertook in a low risk population in China, we observed that body size is a major predictor of risk. Current efforts are attempting to identify additional risk factors and to relate these findings to a variety of measured susceptibility genes, some of which are involved in hormone metabolism. We have also initiated a methologic study to measure endogenous hormones and genetic markers in prostate tissue and to compare these levels with those obtained using serologic samples. Our research has also attempted to advance our understanding of predictors of endogenous hormones. This has included analyses within the control populations of several case-control studies. Efforts are also underway to assess how hormone levels are influenced by a variety of genetic factors, including several hormone metabolizing genes. Efforts are also being made to better understand the functionality of these genes, including effects on endogenous hormones. In an ongoing study of breast cancer in Poland, we plan to use microarray technology to provide clues as to gene products that might be etiologically involved in this tumor. Findings that physical activity can affect endogenous hormones levels have prompted our interest in evaluating relationships with several hormonally-related cancers. Special efforts have been expended on improving exposure assessment. In our Poland study, accelerometers are being used to obtain more objective measures than interview data alone. We are also in the process of establishing a laboratory to increase our understanding of endocrinologic markers that may be most worthy of pursuit in the many studies that are underway.